Optical studies of germanium implanted with high dose oxygen

A model has been developed to explain the greatly reduced reflectivities of Ge samples implanted to doses 1.25–1.5×1018 O/cm2 with 45-keV O+ ions, which have reflectivity values close to zero at 0.7 μm. The model divides the inhomogeneous implanted layer into a series of homogeneous sublayers with different volume fraction and thickness for each sublayer. The complex refractive indexes for every sublayer are calculated using the Maxwell Garnett (MG) and Persson–Liebsch (PL) theories. Using the expressions for the reflectivity of an absorbing multilayer layer systems, the reflectivities have been calculated. The reflectivity curve calculated in the PL approximation is closer to the experimental observations than is the MG approximation over the wavelength range 0.2–3.0 μm.